This is a puzzle of Martin Garnder, taken verbatim from My Best Mathematical and Logic Puzzles:
Two identical bolts are placed together so their groves intermesh. If you move the bolts around each other as you would twiddle your thumbs, holding each bolt firmly by the head so it does not rota...

𝙸 can 𝚠𝚊𝚟𝚎 my hands at you, but I never say goodbye.
You are always cool when with me, even more so when I am high!
If you want 𝚝𝚘 be 𝚒𝚗 too, 𝚏𝚒𝚗d missing sentence/word.
𝙸𝚝 is just simple riddle so… but now I have to go, b𝚢e…
Hint 0:

(Skip this story, that is not part of question, only might be helpful. Sorry for bad English, you can correct things, no stego this time.)
Robot Dan (world smartest vacuum cleaner) and I went to the old isolated lab. It was standard time traveling lab, so kind of cool. However system of time trav...

Quoting wikipedia, The bishop's predecessor in medieval chess, shatranj (originally chaturanga), was the alfil, meaning the elephant, which could leap two squares along any diagonal, and could jump over an intervening piece.

If there's a solution then it has to be of the form "let the BP advance to a3, clear a1 for the BK, allow Ka1, then somehow force the next move to be a2 rather than either Ka2 or Kb1, then give checkmate", and that bit I italicized seems impossible -- the WK can't cover both squares without being adjacent to the BK.

This has got to be the coolest chess puzzle I have ever seen. Shamelessly stolen from here (Which is actually linked from the help center, which is how I found this) which links here. I don't believe anybody has posted this before as a puzzle though.
The question: Can white win in this position?

In the question Who lies and who tells the truth?, rand al'thor explain a) correctly, but he did not display his mathematical approach about the first yellow block at b). Could anyone have time to solve with with logical expressions (modus ponens, syllogism, ...) (full answer for b))?

goes to site to buy ONE thing "Oh hey, there was this other thing wasn't there" adds second item to cart "Oh I should check whether there's anything new for this" adds third item to cart "Oh hey, the site actually recommended something good" adds fourth item to cart

I enthusiastically endorse spending less money on stuff and saving more. (Having said which, I just spent over £2k on a laptop computer so I'm not in the best place to talk. But it's replacing a machine 6 years old and I am generally not very spendy.)

Key requirements: (1) Wide-gamut 4K screen. (I do some graphic-design stuff and accurate colours are useful for that.) (2) Non-shit keyboard. (About half the time I'm sat with a laptop computer, I'm typing on it.) (3) Robust and reliable. (4) Performance that won't make me feel the need to get something newer in three years' time.

I have no idea yet whether I made a good choice of laptop because the damn thing (ordered 2017-05-17) still hasn't actually arrived. (They were very slow to ship, I think because of supply difficulties with the display, and it's still in transit from China. Last I heard, it was in Germany.)

I actually need a working laptop for tomorrow evening, though in a pinch I could use the old one (which now works only when plugged into the mains).

@Sp3000 You will see that one of his more famous works is called "In praise of folly". To appreciate this title you need to know that in Latin that's "Encomium Moriae" and that Erasmus was a friend of Thomas More. Mmmm, multilingual puns.

There's a lovely story about Erasmus that unfortunately is probably false. So Erasmus prepared a widely-used version of the text of the New Testament (note: this is a highly nontrivial problem because there are lots and lots of manuscripts of various dates and provenances and they all have little disagreements with one another). There's an infamous little bit of the New Testament called the "Johannine Comma" that (unlike anything else in the NT) gives fairly explicit endorsement to [...continues

... the (rather odd) Christian doctrine of the Trinity. It appears in some late manuscripts of the Gospel of John, typically mediaeval translations of the Greek text, but not in anything early, and is generally reckoned to be a late interpolation by people wanting to manufacture support for orthodox Christian doctrine. [...continues

So, anyway, supposedly: Erasmus thought this thing was spurious and didn't belong in the original text, but others thought it belonged in the Bible (because it supports the orthodox position, don'tcha know?). Erasmus responded to this with a challenge: Find me one, just one, Greek manuscript that includes the "Johannine Comma", and I will put it in the version of the text I'm preparing. [...continues

And, supposedly, someone found one and presented it to Erasmus, and he said ok, fair enough, in it goes; but it turned out that this Greek text was a translation back into Greek from a much later manuscript, and may in fact have been made only in order to force Erasmus to put that passage in his text.

But, again, it turns out that this story is probably false.

(Well, I think it's funny. My sense of humour is a little peculiar, though. My apologies to anyone who was simply bored by the above.)

One day, a friend has shown me a 5 by 5 grid, challenging me to fill it with numbers from 1 to 25.
Obviously, it is not simple because there are some rules:
The number 1 is placed in the center of the grid
The numbers are placed in ascending order
Only two movements are permitted: moving two bo...